СИСТЕМА АВТОМАТИЧЕСКОЙ ТРАНСМИССИИ, Diagnostic DTC:P0778

DTC Code DTC Name
P0778 Pressure Control Solenoid "B" Electrical

DESCRIPTION

Based on the ON-OFF combinations of the shift solenoid valve SL1, SL2, SL3, SL4 and SL5, the TCM performs gear shifts from 1st gear to 8th gear.

If a circuit related to a solenoid valve is open or shorted, the TCM uses the fail-safe function to turn other solenoid valves ON or OFF. If all solenoid valves are malfunctioning, only the mechanical fluid pressure circuit will function and some manual operation will be possible. If an open or short has occurred, the TCM cuts power to the malfunctioning solenoid valve.

Tech Tips

The following table shows normal operation of the shift solenoid valve SL2 when the shift lever is in D.

Shift Solenoid Valve Operation:
Gear 1st 2nd 3rd 4th 5th 6th 7th 8th
Shift Solenoid Valve SL2 ON ON ON ON OFF OFF OFF OFF
DTC No.

DTC Detection Condition


  1. Diagnosis Condition

  2. Malfunction Status

  3. Malfunction Time

  4. Other

 Trouble Area
P0778

  1. Driving so that gear changes occur

  2. Shift solenoid valve SL2 circuit is open or shorted

  3. 2 seconds

  4. 1-trip detection logic

  • Shift solenoid valve SL2

  • Transmission wire

  • Harness or connector

  • TCM

MONITOR DESCRIPTION

This DTC indicates an open or short in the shift solenoid valve SL2 circuit. The TCM commands gear shifts by turning the shift solenoid valves on or off. When there is an open or short circuit in any shift solenoid valve circuit, the TCM detects the problem, illuminates the MIL and stores a DTC. The TCM performs the fail-safe function and turns the other normal shift solenoid valves on or off. In case of an open or short circuit, the TCM stops sending current to the open or short circuited solenoid.

WIRING DIAGRAM

B001YGZE23
*a Shift Solenoid Valve SL2
*b Transmission Wire

CAUTION / NOTICE / HINT

Note

Perform registration and/or initialization when parts related to the automatic transmission are replaced Click here.

Tech Tips

After performing repair, clear the DTCs and perform the following procedure to check that DTCs are not output.


  1. Perform the D Position Shift Test in Road Test Click here.

  2. Check for DTCs again Click here.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (SHIFT SOLENOID VALVE SL2 - TCM)


    1. B001VK7E02
      Text in Illustration
      *a

      Rear view of wire harness connector

      (to TCM)

      Disconnect the TCM connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A80-3 (SL2+) - A80-2 (SL2-) 20°C (68°F) 5.0 to 5.6 Ω
      A80-3 (SL2+) or A80-2 (SL2-) - Body ground Always 10 kΩ or higher

    OK

    REPLACE TCM Click here

    NG

  2. CHECK HARNESS AND CONNECTOR (TRANSMISSION WIRE - TCM)


    1. Disconnect the C171 transmission wire connector.

    2. Disconnect the A80 TCM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      C171-15 (SL2+) - A80-3 (SL2+) Always Below 1 Ω
      C171-16 (SL2-) - A80-2 (SL2-) Always Below 1 Ω
      C171-15 (SL2+) or A80-3 (SL2+) - Body ground Always 10 kΩ or higher
      C171-16 (SL2-) or A80-2 (SL2-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. INSPECT SHIFT SOLENOID VALVE SL2


    1. B00201YE13
      Text in Illustration
      *1 Shift Solenoid Valves SL2

      Remove the shift solenoid valve SL2 Click here.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      Terminal 1 of the shift solenoid valve SL2 - Terminal 2 20°C (68°F) 5.0 to 5.6 Ω

    3. Apply 12 V battery voltage to the shift solenoid valve and check that the valve moves and makes an operating noise.

      OK
      Measurement Condition Specified Condition

      • Battery positive (+) with a 21 W bulb → Terminal 2

      • Battery negative (-) → Terminal 1

      		 Valve moves and makes an operating noise

    OK

    REPAIR OR REPLACE TRANSMISSION WIRE Click here

    NG

    REPLACE SHIFT SOLENOID VALVE SL2 Click here